GLOSSARY 147
GLOSSARY
ac Alternating Current. Electric current that reverses its direction of flow
periodically according to frequency measured in hertz, or cycles per
second.
CO Central Office. Another name for the Line Card (LC), a card in the VCN
AC chassis; the card provides an Ethernet port and an LMI port.
Constellation The digital bit rate per analog symbol.
dc Direct Current. Electric current that does not reverse its direction of
flow.
DS Down stream. The direction in VDSL towards the user workstation.
EMC Electromagnetic compatibility
HDLC High-level Data Link Control. HDLC is a bit oriented, synchronous
protocol that applies to the data-link message packaging layer (layer 2
of the ISO/OSI model) for computer communications . messages are
transmitted in units called frames, which contain differing amounts of
data but which must be organized in a particular way.
Hz Abbreviation for hertz, electrical cycles pr second.
ID Identifier used for the management login procedure.
ISP Internet service Provider. A business that supplies Internet connectivity
services to individuals, businesses and other organizations within a local
area.
IT Information Technology
Krone connectors Connectors on patch cords used to connect or jumper patch panels
LAN Local Area Network. A group of computers and other devices dispersed
over a relatively limited area and connected by a communications link
that enables every device to interact with any other on the network.